Metalworking process



Patented Dec. 16, 1941 FFICE l 6 Y METALWOBKING rnocnss Wayne E. Martin,Temple, Pa asslgnor to The Beryllium Corporation, a corporation ofDelaware No Drawing.

Application July 1"1, 1940,

v Serial No. 345,978 7 Claims. (Cl.14811 This invention relates tometallurgy and more particularly to metal working and has for its objectthe provision of a method of working-cast beryllium-copper alloyscontaining beryllium within the range 1.52.10% to homogenize thestructure thereof thereby to render the same better adapted for severecold mechanical deformation and to age hardening heat treatment. Anotherobject is to provide a method of working cast beryllium-copper alloyscontaining l.52.10% beryllium to effect substantially completeelimination therefrom of the cast beta constituent normally presenttherein. Still another object is to provide a beryllium-copper alloycontaining beryllium 1.52.10%" that is substantially free from east betaconstituent, homogeneous in structure, and more readily cold workableand more uniformly age hardenable. Other objects and advantages will beapparent as the invention is more fully hereinafter disclosed.

In the manufacture of beryllium-copper alloys,

the same are first'prepared in the molten state and then are cast intosuitable sized ingots as heretofore practiced in the manufacture ofother type alloys. Due to the nature of the phase diagram, .in thecourse of freezing a marked cored structure results in beryllium-copperalloys, the precise character of which varies somewhat with respect tothe rate of cooling the ingot. In general, the first nuclei to freezeare of low beryllium uted throughout the same. The following methcontent(about 1%), and while the metal subalpha solid solution around each betaparticle during solution annealing.

The cold workability and age hardening as well as the physical andmechanical properties of beryllium-copper alloys are directly eifectedby the presence of this beta constituent and by the uniformity ofdistribution of beryllium in the alloy. In general, binaryberyllium-copper alloys containing-less than about 1.5% beryllium arerecognized as being cold workable, but not signiflcantly age hardenable;those containing beryllium within the range 1.5 to 2.10% are recognizedas being both cold workable and age hardenable; and those containingover about 2.10% beryllium are recognized as being of limited coldworkability depending upon the beryllium content but age hardenable andas being more suited for use as casting alloys. However, in those alloyscontaining beryllium within the range 1.5

um is with difliculty eliminated from the alloy and K the berylliumcontent thereof uniformly distribod has been found by me to be mosteffective in obtaining re-solution of the beta constituent and theuniform distribution of the beryllium content throughout the alloy. t Ifirst subject the cast metal to a prolonged heating approximating three(3) hours at a temperature within the range 1400-1500" 'F'. to obtainpartial re-solution of the beta constituent. I then subject the castingto hot mechanical deformation on a falling temperature gradient,starting at temperatures approximating 1450 F., continuing thedeformation until about 700 R, the extent of deformation being such asto effect partial fracture of the beta particles and a chanicaldeformation starting at 1450" F. as described above.

The beta solution heating and hot mechanical deformation operations arerepeated as frequently as may be found necessary with any given alloycomposition within the range Lil-2.10% beryllium to effect re-solutionof the beta constituent before the thickness -of the ingot has beenreduced to that at .which cold mechanical deformation is to beinitiated. The frequency of application of the two operations will varywith any given alloy with respect to the size of the beta particlespresent, and-in general with any given size beta particles will increasewith increase in beryllium content within the range beryllium 1.5-2.10%.As the beryllium content approximates 1.9%, it is necessary even aftercold working is initiated to subject the cold worked metal to one ormore intermediate h'eatings at a temperature within the range 1400-1500F. for a prolonged time interval approximating three (3) hours to effectfinal re-solution of the last traces of the beta constituent,particularly if originally present in relatively large particles.Following each heating within the range 1400- 1500 F. that is appliedafter cold working is initiated, the alloy should be quenched or rapidlyair cooled to preserve the solid solution structure obtained.

As one specific embodiment of the practice of the present invention, theworking method employed on the LSD-1.90% beryllium alloy will bedescribed.

This alloy is usually cast as four inch (4") rounds approximating 24inches in length. I first heat these cast ingots in a furnace underatmospheric conditions inhibiting alloy deterioration to a temperatureapproximating 1475 F. and maintain the ingot at this temperature for atleast three (3) hours. I have found that heating for periods of timelonger than three (3) hours does not appear to effect an appreciablygreater amount of re-solution of the beta constituent.

I then subject the heated ingot to hot mechanical deformation, as abovedescribed, until about 35-40% reduction in area has been obtained. Thehot worked metal is again soaked at about 1475 F. for another three (3)hours. Following the second heating, the metal is again hot worked toabout 35-40% reduction in area and again soaked at about 1475 F.

Where the beryllium content approximates 1.50%, it will be found thatthe major portion of the beta constituent has been redissolved at theend of the third heating, or that a sufficient amount of the same hasbeen redissolved to permit the metal to be mechanically deformed in thecold at least to a 50% reduction in area. Where the beryllium contentapproximates 1.90% and the initial particle size of the beta constituentis not excessive, it will also be found that at the end of the thirdheating the major portion of the beta constituent has been dissolved andthat the metal can be cold worked to about 50% reduction in area.

Accordingly, at the end of the third heating I generally quench orrapidly air cool the alloy and initiate cold working on all alloyscontaining 1.5 to 1.90% and subject the same to about 50% reductioninarea. The alloy is then given a fourth reheating within the range1400-1500 F. for another three (3) hour period and quenched or rapidlyair cooled thereafter.

Following this heating, it will be found that the alloys aresubstantially free from beta constitu'ent and are of substantiallyuniform composition throughout, as is reflected in the cold workingproperties and in the extreme uniformity in age hardening and physicalproperties of the alloy.

In those alloys containing between 1.90-2.10% beryllium, the re-solutionof the beta constituent is more dimcult by reason of the fact that theamount of beta is greater and the particle size of the same is usuallylarger. However, by following the practice hereinabove given withrespect to the 1.5-1.90% beryllium alloys on the same sized cast ingots,modified to the extent of increasing the total number of hightemperature heatings and hot working operations by roducing the per centreduction of area during each hot working operation and increasing thenumber of anneals during subsequent cold working, a final cold workedproduct may be obtained even with the 2.10% beryllium alloy that issubstantially free from beta constituent.

For example, the 2.10% beryllium alloy in four inch (4") round casting,when subjected to sub-- stantially the same total mechanical deformationgiven the 1.5-1.90% Be alloy in three (3) hot working stages instead oftwo (2) each preceded and followed by a three (3) hour soaking at atemperature within the range 1400-1500 F., will be found to be readilycold workable to at least at 30% reduction in areaif quenched or rapidlyair cooled following the fourth soaking.

By then subjecting the metal to a plurality of alternate cold workingand heat treating operations, each cold working operation producing a30-40% reduction in area and each heating being a soaking for aboutthree (3) hoursv at a temperature within the range 1400-1500 F., the

final cold worked metal will be found to be entirely free from beta andof uniform composition throughout. For example, I prefer to effectreduction of the four inch (4") round casting of the 2.10% Be alloytoabout one inch (1") in four (4) hot working stages. After the fifthsoaking heating I quench or rapidly air cool the one inch (1") hotworked material and then subject it to the following working method:

(1) Cold work to about (2) Anneal 3 hours at 1475 F., quench.

(3) Cold work to about A.".

(4) Anneal 3 hours at 1475 F., quench.

(5) Cold work to about $6".

(6) Anneal 3 hours at 1475 F., quench.

(7) Cold work to desired final, or near final,

size.

The product at the end of step (6) usually is completely free from beta,and can be cold worked as much as reduction to desired' sized wire orstrip without difiiculty. It is to be recognized that where material ofA." and t4," sizes, substantially free from beta are desired, largersized starting ingots may be employed. Alternatively, by increasing thetotal number of beta-solutioning heatings with interspersed hot or coldwork stirring operations, it is also possible to obtain beta-freematerial at larger sizes.

The above disclosure relates more specifically to the so-called binarytype alloy. As hereinabove disclosed, the particle size and distributionof the beta has an important bearing on the effectiveness of any givenmethod of working 101- lowed as hereinabove described. The particle sizeand distribution of the beta is materially affected by the rate ofcooling the casting. I have also found it to be markedly affected byalloyed percentages of one or more of the iron group metals within therange .10-.50%.

The iron group metals (Fe, Co and Ni) each appear to form beryllidecompounds when present in amounts above the'solubility limit of each(which in general approximates .10%). Each of these metals form acharacteristic type of beryllide compound readily identifiable one fromthe other on microscopic examination.

These beryllide compounds appear to have a very pronounced effect on theparticle size and distribution of the beta constituent in the castalloy, causing the same to be smaller and more 2,2oo,ooe 3 'uniformlydistributed, probably by providing a larger number of nuclei on whichcrystallization may initiate. However, these beryllide compounds per seare exceedingly hard and brittle, and when present in any considerableamount above about .50% deleteriously afiect the cold workability of thealloy. I have found that par.- ticularly in the alloys containingbetween 1.90-, 2.10% Be, I may employ as high as .50% of one or more ofthe metals Fe, Co and Ni, preferably Co without substantial detriment tothe cold working properties of the alloy, but I have found r itpreferable in most instances to use not over 20% of one or more of thesemetals Fe, Co and stituent if following cold reduction down to about themetal is given one more such betasolutioning annealing. Thereafter, themetal can the desired final size the's'aid alloy is again reheatedwithin the range 1400,-1500 F. for a pro- 'longedtime interval effectiveto obtain re-solution of the remaining beta particles and uniformdistribution of the beryllium content of the alloy throughout the mass.and then is cooled rapidly to atmospheric temperatures to condition thesame for cold mechanical deformation to final size.

3. The method of claim 1, wherein during cold mechanical deformation aplurality of intermediate heat treatments at a temperature within the.range 1400-1500 F. is applied thereto each for a time interval effectiveto obtain further resolution of the remaining beta particles and touniformly distribute theberyllium content of, the alloy throughout themass, each said heating being followed bya rapid cooling'to preserve thealphamatrixobtained and to condition thealloy be cold worked to finalsize with intermediate I half hour anneals to remove work hardening asheretofor customary in the art and on heat treatment to age harden willbe found to be uniformly responsive and to have improved physicalproperties.

In an alloy containing 2% Be, I have found .30% Co to be very effectivein producing a final cored structure in the cast ingot with resultantbetter response to the above described working method. In an alloycontaining 1.5% Be, I have found 00 as low as 125% to be equally aseffective as 20% Co in obtaining a finer'cored structure and both alloysevidence substantially iden: tical cold working properties followingre-solution of the cast beta constituent in accordance with the presentinvention.

- From the above description of the present invention it is believedapparent that many modiflcations anddepartures may be made thereinwithout essential departure therefrom and all such are contemplated asmay fall within the scope of the following claims.

What I claim is:

1. The method of working cast beryllium-copper alloys containing 1.5 to2.10% beryllium, which comprises heating the alloy to a temperaturewithin the range 1400-1500 F. for a time interval at least sufllcient toeffect substantial re-solution of the cast beta particles dispersedtherethro'ugh, mechanically deforming the alloy on a falling temperaturegradient initiating at a temperature within the range 1400-1500 F. andterminating at about 800 F. to an extent at-least effective to disturbthe alpha phase surrounding the beta particles, reheating the said alloyto within .the range 1400-1500 F. for a time interval effecting furthersubstantial solution of the said beta particles, and repeating the notmechanical deformation and reheating operations until the remaining betaparticles are insufficient to materially interfere with cold mechanicaldeformation, then rapidly cooling the said alloy from the final heatingto condition the same for cold mechanical deformation.

2. The method of claim 1, wherein following cold mechanical deformationto a size larger than for further cold'mechanical deformation.

4. The method of working cast BeCu alloys containingBe 1.5-2.10% toobtain a homogeneous structure and uniform. distribution of the Becontent therein, which comprises subjecting the cast alloy to aplurality of successive and alternate heat treating and .'hot' workingoperations, each said heat treating operation being for a prolonged timeinterval at a temperature within the range 1400-1500" F. and each saidhot working operations being on a falling temperature gradient initiatedat about 1450 F. and terminating at a temperatureapproximating but notbelow about 700 F., the extent of deformation effected in each saidworking operation being at least sufficient to substantially break upthe stabilized metal structure formed during the preceding heat 7treatment operation.

prises first heating the alloy to temperatures within the range1400450091". for a time interval at least suflicient to obtain Besaturation in the alpha matrix immediately adjacent each beta particle,then hot working the alloy on a falling temperature gradient from atemperature approximating 1450" F."to a temperature approximating butnot below about 700 F., the extent thereof being at least sufllcient toeffect a general breaking up of the Be saturated alpha matrix obtainedduring the first heating operation and the locating of unsaturated alphamatrix in a position to dissolve more Be from the said beta particles,again reheating as in step one above and again hot working as in steptwo above, and repeating the said heating and working steps one and twountil substantially complete re-solution of the said beta particleshasbeen effected and a homogeneous cold workable structure has beenobtained. v .i

6. The method of working cast Be.Cu alloys containing from 1.5-2.10% Beto eliminate therefrom cast beta particles and to produce a subsiantially homogeneous metal structure therein, which comprises subjectingthe cast alloy to an extended heating at temperatures within the range1400-1500 F., the time interval of said heating being at leastsuflicient to obtain partial re-solution of the beta particles in thealpha 4- x i a 2,266,056

mating 1450 F. and continuing to a temperature approximating but notlower than about '(00" F. the extent of such deformation being at least"sufllcient to effect a general breaking up of the said alpha phase,reheating the mechanically deformed metal to within the said range1400-1500.

F. for a time interval at least sufllcient to obtain furtherre-solutionof the said beta particles and again mechanically deforming attemperatures within the range 1450-700 F., and repeating the saidheating and working operations until substantially complete re-solutionof the said betaparticles is eflected.

"l. The method of effecting the re-solution of beta-particles in castberyllium-copper alloys containing 1.5 to 2.10% Be, which comprisessubjecting the cast alloy to alternate beta solution ing heat treatmentsand hot working operations, each beta solutioning heat trea operationbeing at a'temperature within the range 1400-1500" F., for a prolongedtime interval to obtain beryllium saturation in the alpha phaseadiacent'to and surrounding the said beta particles. and each hotworkihg operation initiating at a temperature approximating 1450' F. andbeing continued 7.

on a falling temperature gradient to temperatures approximating but notsubstantially below about 700 -F., the extent of deformation during

